Adding my two cents here. Unfortunately, I had issues with Share-A-Cart recently, it's not as good as expected anymore because they started pushing paid upgrades for basic sharing. Before I suggest another free tool, quick question: is your mom going to be checking out on a computer or her phone? If she's on a phone, some extensions won't work at all, so we might need a different workaround.

I have tested a few of these for coordinating team purchases. Here is how the main ones compare:

• Cart to Link: Very lightweight, doesnt require an account, and just generates a simple link you can text.
• Share-A-Cart: Has more features but the interface is cluttered and it asks for a lot of browser permissions. I usually stick to the first one since it is safer and simpler for non-tech users.

Commenting to find later

Saw this earlier and wanted to chime in! I used Share-A-Cart last Christmas for family gifts and honestly it was amazing, even with the messy UI. The other option I tried was just making a shared Amazon Wish List. The list is safer since it is built-in, but the extension is way faster for actual checkout. Let me know if you need help setting it up!

Finally someone says it. Ive been thinking this for a while but wasnt sure.